Process of rolling metals



2 Sheets-Sheet l I INVENTORS eWaZZgr/Jgmes ATTORNEY Nov. 28, 1933. R.CLAPP ET AL PROCESS OF ROLLING METALS Filed March 25, 1929 N .rli ZEWLALH///1 Lawn 11m K Cldjd]? NOV.28,1933. L R CLAPP rA I L93Q582 PROCESS OFROLLING METALS Filed March 25, 1929 2 Sheets-Sheet 2 INVENTORSZ22zv7zv1ae.22 (72559? ATTORNEY Patented Nov. 28, 1933 UNITED STATESPATENT OFFICE 1,936,582 lPlltQQESS OF ROLLING METALS Application March25, 1929. Serial No. 349,89 ll 13 Claims. (Cl. 80-80) This inventionrelates to the production of thin sheets of ductile non-ferrous metals,and more particularly, to the cold rolling of such metals from a slab orplate to produce a thin 'wide sheet of uniform thickness. The inventionrelates specifically to the cold rolling of cop-. per plates andprovides for a reduction in thickness without intermediate heattreatment in excess of 50%.

In accordance with the present invention the sheets of a width in excessof 22", are cold rolled in a plurality of steps to effect a reduction inthickness in excess of 50% and to produce a sheet in which the variationin thickness is not over 5%.

It has been found that in rolling a sheet of metal the force applied bythe rolls may be resolved into horizontal and vertical components. Thehorizontal component tends to tear the sheet apart and to pull themetalaway from the point of rolling, whereas the vertical componentrepresents pure compression. In so rolling the sheet as to reduce thethickness thereof in a single pass by a considerable value, such as 15%to i0%, the horizontal component becomes sufiiciently large to .tear orotherwise damage the sheet unless the same is of considerable thickness.

The present invention further provides for so controlling therelationship of these components I as to prevent tearing of the sheetwhile obtaining a substantial reduction. For this purpose the slippagebetween the roll and the rolled sheet is controlled. As the slippageincreases the horizontal component is decreased with respect to thevertical component. By suitably controlling the slippage, therefore, thehorizontal component may be reduced to a value below that at which thethin sheet would become torn.

It is also necessary to control the heat distribution in the roll inorder to prevent uneven expansion thereof and to maintain acomparatively straight and parallel line of contact with the metal. Thismay be accomplished differentially in a longitudinal direction of therolls and the total heat must be controlled within given limits.

The present invention further provides for utilizing a single medium forcontrolling both the heat of the rolls and the slippage. It will beapparent from the'specification that a plurality of mediums may beemployed if desired in particular instances although the single mediumis preferable by reason of the simplicity of operation and the reductionin cost.

. pressed air.

In initiating the operation, that is, in making the first pass of metalbetween the rolls, the plate is comparatively thick, for example ormore, and a comparatively large horizontal component may be employed.During this operation, therefore, the rolls may be cooled with a mediumwhich will not appreciably affect the slippage thereof, for example, ablast of com- Means is also provided for controlling the application ofthe cooling medium at various points longitudinally of the rolls wherebythe cooling eifect may be regulated as nec-' essary to maintain an evenflat surface. In'subsequent passes, as the thickness of the material isreduced, a cooling medium having lubricating properties may be employedwhereby the slippage is increased and the horizontal componentcorrespondingly decreased. For intermediate passes water has been foundto be a satisfactory medium and serves to cool the rolls while at thesame time permitting a certain amount of slippage. For the final passes,however, as the sheet becomes thin, it is necessary to still furtherincrease the slippage and for this purpose an oil may .be employed whichwill serve as a cooling medium and also to suitably reduce the frictionbetween the roll and the metal and cause the degree of slippagerequired. During all of these steps a sufllclent pressure is employed tomaintain the contacting surfaces of the rolls in parallelism as will bemore specifically pointed out hereinafter.

The invention further consists in the new and novel features ofoperation and the new and original arrangements and combinations ofsteps in the process hereinafter described and more particularly setforth in the claims.

The invention more specifically is carried out in any well known type ofmill by the use of rolls between which a plate of metal may be passed.When pressure is applied to the ends of the rolls to produce thenecessary compression, a certain bending will take place which wouldnormally tend to form a slight crown on the rolled sheet. The rolls areaccordingly crowned in such manner that when pressure'is applied theline of contact with the sheet is substantially straight, longitudinallyof the roll thereby forming a substantially straight rolling surface. Incertain instances a crown in the form of a catenary has been foundsuitable for this purpose. It is obvious that the amount of crown willdepend upon the total pressures to be employed. It is also desirable touse rolls of a comparatively small diameter since the total contactingsurface of said fective shape of the rolling surface.

rolls is less than with those of large diameter, and a smaller totalforce may be used to give the desired pressure per square inch.

The rolling operation produces heat which is absorbed by the rolls andmust be removed therefrom. If the temperature of the rolls is permittedto vary an uneven expansion thereof will take place, with a consequentchange in the ef- It is accordingly desirable to control the heatlongitudinally of the rolls in such manner that the desired rollingsurface is maintained throughout the operation. This may be accomplishedby circulating a cooling medium internally of the roll or applying acooling medium externally thereof or both as will be more fully pointedout hereinafter. In starting the operation it may even be necessary tosupply heat to certain portions of the rolls,

- such as the ends, in order to prevent an uneven expansion while theyare becoming heated to their operating temperature.

Although the size of roll may vary within limits depending upon thematerial employed and the width of the sheet being rolled, it has beenfound that a roll having a diameter less than 16" is preferable inrolling a sheet having a width of 42". This diameter may be decreased,however, as the operation progresses, using a roll having a diameter ofsome 12" for the final passes.

A plate of ductile non-ferrous metal such as sheet copper having athickness of approximately is first passed between rolls formed asabove, preferably while maintaining their outer surfaces dry. Thisfacilitates the rolling operation and eliminates slippage of the roll,so that the horizontal component of the force exerted thereby ismaintained as great as possible with respect to the vertical component.For this operation the roll may be cooled internally and/or it may becooled by a blast of gaseous cooling medium. such as compressed air,which may be blown against the outer surface thereof. This blast ispreferably controlled separately at various points longitudinally of theroll so that the heat can be suitably regulated for maintaining thedesired rolling surface.

The rolling operation described above is continued by successive passeseither between the same set of rolls or between additional sets, and asuitable medium is applied thereto to control the slippage as desired.In intermediate passes it has been found that water may be employed forcooling the rolls and may beapplied to the outer surface thereof inplace of the compressed air utilized in the initial passes. The waterhas slight lubricating properties and causes a certain amount of slip totake place between the roll and the rolled sheet, thereby reducing thehorizontal component to the desired value. It is to be noted that thewater operates both as lubricating medium and a cooling medium, and maybe controlled as desired for these purposes. If an additional amount ofcooling is required it may be obtained by circulating the cooling mediuminternally of the roll as above mentioned, by varying the temperature ofthe water, or. by using a combination of water and compressed air.

For the later passes, as the sheet becomes thin, the horizontalcomponent of the force exerted by the rolls must be considerably reducedto avoid tearing. This is accomplished by applying oil to the outersurface of the rolls, the lubricating properties thereof serving tocause slippage to take place. Various types of oil may be employed inaccordance with the amount of slippage required.

Kerosene has been found suitable for certain passes, while for other orlater passes an oilhaving higher lubricating properties may be required.It is essential in any case to utilize an oil which will not leave aresidue on the rolls. and thereby tend to corrode the surface of therolled sheet. While various types of oil may be employed for lubricatingpurposes it is preferable to utilize an oil which also possesses markedcooling properties. Obviously, a combination of oil and compressed airmay be employed if desired. The cooling medium selected will depend onthe thickness of the metal being rolled and the total reductionrequired. A single medium only may be employed if advisable in aparticular case.

The novel process hereinabove described may be carried out with avariety of apparatus. In the drawings annexed hereto an apparatus isshown which is suitable for the purposes of the present invention. Inthe drawings, like numer-- Fig. 1 is a median transverse verticalsection of a two-high rolling mill with associated equipment;

Fig. 2 is a rear elevation of the mill shown in Fig. 1 showing thearrangement of the cooling device; and

Fig. 3 is a detail of a roll with associated cooling apparatus.

Referring more specifically to the drawings, the mechanism showncomprises a two-high mill with the usual standards 10, and having rolls11, 12 mounted therein in the usual manner. The rolls may be secured inplace between the standards by locking nuts, indicated generally at 13.The rolls may be adjusted by the usual means, such as screws 14 mountedin the standards. The rolls l1 and 12 are centrally crowned, asindicated at 15, to permit the proper rolling of the sheets duringoperation and being convex will not cause the sheets being rolled to bedistorted. The crown of the rolls, as shown more particularly in Fig. 2,is shown very marked, but in practice the actual crown foimed on thesurface of the rolls would amount to a few thousandths of an inch, moreor less, depending upon the material to be worked and other designfactors. The rolls, as indicated more particularly in Fig. 3, may beinternally cooled and for this end are provided with an internal grooveor channel 20 into which is fitted an inlet pipe 21, fastened inposition within the channel 20 by means of a perforated spacer 22. Theshaft 23 is secured to the roll proper in the usual manner, and isitself hollowed out to provide a central channel 24 adapted to registerwith the channel 20 of the roll. The channel 24 is provided with areduced extension 25 into which is tapped the end of tube 21. The tube21 is thus supported between the shaft 23 and the spacer 22. The shaft23 is apertured, as indicated at 26 and 27, to provide an inlet andoutlet for the cooling fluid from the stuffing box 28 which may beprovided with inlet and outlet pipes 29, 30'.

The external cooling of the rolls and the supplying of sufficient andproper lubricants and cooling-media is accomplished in the followingmanner:' A lubricant feed line 30 is secured to one of the standards bysuitable brackets 31 and is thereafter extended across the entire widthof the roll, being secured in the opposite standard in any suitablemanner, as indicated at 32. A plurality of cocks 33 are tapped into Ts34 and are severally provided with the usual controls 35, permittingindividual operation of the several cocks. This arrangement permits thefeeding of lubricants onto the forward aspect or face of the rollsduring operation and further permits the distribution of the lubricantin any desired spot or spots and in any amount.

To provide for the cooling of the rolls after the lubricant and the rollsheets have been stripped by means of the stripper plates 36,air-cooling means may be provided. This system comprises a plurality ofspray pipes 37, 38, 39 extending over the rear faces of the rolls to adesired length, as shown. These pipes are tapped into manifolds sohaving a common supply pipe 41 which is teed onto a main supply pipe 42,the latter being provided with a control valve 43. The several spray orfeed pipes 37, 38, 39 are each provided with valves a l, 45, 46. Themanifold pipe 41 may be secured to the standard by brackets 50.

The improved apparatus above described may be maintained at a desireduniform temperature, insuring the desired parallelism of the rollsurfaces in operation by not only lubricating the material being rolled,but also by applying cooling fluids such as air to the surface of therolls. By having spray pipe 37, 38, 39 of differential lengthoperatively associated with the rolls, any portion or portions of theroll may be cooled and maintained at the desired operating temperature.

By operating the process as above described a large reduction in crosssectional area may be obtained without the necessity for annealing thesheet. In fact it is possible to obtain a total reduction in crosssectional area of as great as 98%. The reduction is the greatest in theinitial passes where the thickest material is being acted upon and maybe as high as 40% which varies down to some in the final passes. Bysuitably selectthe crowning of the rolls with respect to thecompressional force employed, the surface of the a rolled sheet may bemaintained substantially flat throughout the entire operation. A sheet.018" thick and 42 wide has been produced in this manner with avariation in thickness of less than The present process is capable offorming a wide flat sheet by uninterrupted cold rolling operations. Thesheet may be in excess or in width and has been produced on a commercialscale of a width of a2" and a thickness of .1318 from a plate having anoriginal thickness of %3". It has heretofore been considered impossibleto produce a sheet of this width with a comparatively fiat surfacewithout interrupting the rolling operation for intermediate annealing.The tensile strength of the present product is increased progressivelywith successive rolling operations and in the finished sheet may be inexcess of 55,000 lbs. per square inch, a figure which could not beobtained if intermediate annealing operations were resorted to. Theprocess therefore provides for rolling on a commercial scale, sheetshaving a width and tensile strength greater than that heretoforeobtainable and for efiecting a greater reduction in cross sectional areawithout annealing.

Althoughcertain novel features of the invention have been described andare pointed out in the annexed claims, it will be understood thatvarious omissions, substitutions and changes in the several steps of theprocess and in its operation and in the form and details of theapparatus illustrated may be made by those skilled in the art withoutdeparting from the spirit of the invention.

What is claimed ist 1. The process of cold rolling sheets of non-'ferrous metal which comprises successively passing said sheets throughrolls, whereby a given per centage reduction of thickness of said sheetis obtained and controlling the slippage of said rolls in inverseproportion to the thickness of said sheet, whereby tearing of said sheetis avoided and a uniform fiat product is obtained.

2. The process of cold rolling sheets of nonferrous metal whichcomprises passing said sheets through rolls whereby the thicknessthereof is progressively reduced, and progressively increasing theslippage of said rolls with successive passes.

3. The process of cold rolling sheets of nonferrous metal whichcomprises passing said sheets between a set of rolls a plurality oftimes, applying various lubricants in successive roll passes forincreasing the slippage of said rolls as the sheets become thinner, andutilizing said lubricants as cooling mediums for regulating the heat ofsaid rolls.

4. The process of cold rolling sheets of nonferrous metal in a pluralityof stages which comprises making a plurality of passes of said sheetsbetween rolls, applying a cooling medium to said rolls during the firstpasseaapplying a second cooling medium having slight lubricatingproperties to the rolls during intermediate passes and applying a thirdcooling medium having substantially greater lubricating properties tosaid rolls during the final passes.

5. A method of cold rolling non-ferrous metals to produce a sheet havinga substantially uniform thickness, which comprises successively passingsaid sheet between a plurality of rolls formed to normally have a convexsurface, applying pres= sure to the ends of said rolls sufficient toform a substantially straight contacting surface, controlling the heatdistribution longitudinally of said rolls and variably increasing theslippage of said rolls as the thickness of said sheet is decreased.

6. The process of cold rolling a sheet of ductile metal to efiect asubstantial reduction in thickness thereof, which comprises successivelypassing said sheet between squeezing rolls having a crowned surface andapplying suficient pressure to said rolls to produce a substantiallystraight rolling surface and to make a reduction in thickness in. eachpassage of said sheet in excess of 15% in a single pass, controlling thetempera= ture of said rolls to maintain said substantially straightcontacting surface and produce it rolled sheet having substantiallyparallel surfaces, and controlling the slippage of said rolls wherebythe horizontal component of the force supplied thereby decreases as thesheet becomes thinner.

l. The process of cold rolling ductile metal which comprises passingsaid metal between rolls having a crowned surface, applying sumcientpressure thereto to form a substantially straight contacting surface,cooling said rolls during the initial pass by a blast of compressed air,utilizing water as a cooling medium for said rollers during intermediatepasses and utilizing oil as said cooling medium during the final passes,thereby to increase the slippage of the rolls as the metal becomesthinner whereby the horizontal component of the force exerted is reducedand tearing of the sheet is prevented.

8. The process of cold rolling a ductile metal such as copper into thinsheets of a thickness of less than so thousandths of an inch and a widthexceeding 22 inches, which consists in roll- Mill illlll accurateparallelism between the faces thereof, and applying successivelylubricants of different viscosities to the rollsdiu'ing certainsuccessive passes of the sheet.

9. The process of cold rolling a ductile metal such as copper in widesheets of a uniform thickness throughout, which consists in forming thefirst passage of the rolls with a reduction which will remove anyinequalities of thickness and produce a substantially flat plate,rolling said plate with reductions sufllcient normally to heat therollsunequally in different parts thereof and controlling the temperature ofsaid rolls by successively applying cooling mediums having dif-' ferentheat conductive properties to said rolls as the sheets become thinnerthereby to maintain a substantially uniform temperature throughout thelength thereof.

10. The process of cold rolling sheets of nonferrous metal whichcomprises passing said sheets through rolls whereby the thicknessthereof is progressively reduced, and progressively increasing theslippage of said rolls as said sheets become thinner. l

11. The process of cold rolling copper into thin sheets having athickness of less than .009 inches and a width exceeding 22 inches,which consists in passing the sheet between rolls while maintainingaccurate parallelism of the faces thereof and applying successivelylubricants of increasing viscosities during certain successive passes ofthe sheet whereby the slippage of the sheet is increased as the metalbecomes thinner.

12. The process of cold reduction of a sheet of copper which consists inpassing a sheet of said metal rapidly and without intermediate annealingthrough small accurately crowned rolls with the crown designed toproduce a substantially flat sheet on reductions per pass of 15%-40%,.removing the large amount of heat generated by these heavy reductionsby applying a suitable cooling medium to said rolls and varying thecooling medium and amount of heat removal selectively across the faceof-the roll to maintain a flat rolling surface.

13. The process of cold reduction of a sheet of copper which consists inpassing a sheet of said metal rapidly and without intermediate annealingthrough small accurately crowned rolls with the crown designed toproduce a substantially flat sheet on reductions per pass of l5%-40%.Providing adequate means for removing the large amount of heat generatedby 'these heavy reductions and increasing the slippage between thecopper and the roll as the former becomes thinner whereby tearing of thesheet is prevented.

LAWRENCE R. CLAPP. GEO. WALTER JAMES.

